1. Field of the Invention
The present invention relates to a method of forming a copper wiring in a semiconductor device, and more particularly to a method of forming a copper wiring in a semiconductor device to produce a thin copper film of superior quality as well as to realize repeatability of a copper deposition process by establishing the Metal Organic Chemical Vapor Deposition (MOCVD) process technology using the 1,1,1,5,5,5-hexafluoro-2,4-pentadionato(vinyltrimethoxysilane)-copper(I) {(hfac)Cu(VTMOS)}compound as a copper precursor.
2. Description of the Prior Art
While the semiconductor industry moves to the Ultra Large Scale Integration (ULSI) and the geometry of a device reduces to the sub-half-micron area, circuit density from the aspect of performance improvement and reliability increases. According to such demand, a thin copper film may improve reliability of a semiconductor device because the melting point of the film is higher than a temperature of aluminum and resistance of the film against Electro-Migration (EM) is large. Also, since a thin copper film can increase signal transmission speed as its specific resistance is low, the film is used as an interconnection material that is useful for integration circuits.
In a method of forming a copper wiring, the copper deposition process is an important process for realizing fast devices and high integration devices. Applied technology for copper deposition includes Physical Vapor Deposition (PVD), electroplating, electroless-plating and MOCVD. For copper deposition by MOCVD in the above methods, a copper precursor should be developed for easy deposition because of much influence by a copper precursor. It is also essential to develop a delivery system that can safely deliver a copper precursor for the method.
For copper deposition by MOCVD, such Liquid Delivery Systems (LDS) as the Direct Liquid Injection (DLI) manufactured by xe2x80x9cMKSxe2x80x9d and the Control Evaporation Mixer (CEM) by xe2x80x9cBrongkhorstxe2x80x9d are used. Copper deposition by MOCVD is performed by resolving the compound including copper called a precursor in such an LDS. For a copper precursor used in MOCVD, a CuI compound, whose deposition speed is rapid compared with a CuII compound because of high vapor pressure, to allow thin copper film deposition of high purity at a low temperature of 150xc2x0 C. through 250xc2x0 C. was developed since such CuII compound as the 1,1,1,5,5,5-hexafluoro-2,4-pentadionato-copper(II) {(Cu(hfac)2} compound of low vapor pressure was developed. In the CuI compounds developed until now, the 1,1,1,5,5,5-hexafluoro-2,4-pentadionato(trimethylvinylsilane)-copper(I) {(hfac)Cu(TMVS)} compound developed by xe2x80x9cSchmacherxe2x80x9d exists as liquid form at a room temperature, and is a representative precursor for MOCVD used most in the world at present because the compound allows thin copper films of high purity to be deposited at a low temperature. A problem of a (hfac)Cu(TMVS) compound, however, is that it is degraded in storing at a room temperature in spite of such merit. Therefore, the compound has some difficulty in applying to the manufacturing process of a semiconductor device for process repeatability of the compound. It is very difficult to keep repeatability as far as a new LDS for safe delivery is not developed because the vapor pressure of the compound is rather high in the developed precursors but it is rather low to keep repeatability in the existing LDS. Also, another difficulty is that very constant temperature should be kept because the interval between a vaporization temperature and a condensation temperature of a (hfac)Cu(TMVS) compound is very short. xe2x80x9cSchmacherxe2x80x9d has announced that a (hfac)Cu(TMVS) compound may be used safely for 1 year, using the stabilizer.
To settle the problems of the (hfac)Cu(TMVS) compound, xe2x80x9cUp Chemicalxe2x80x9d developed the (hfac)Cu(VTMOS) compound as a precursor. A (hfac)Cu(VTMOS) compound is known that degradation and deterioration of the compound is not generated at a room temperature, compared with the (hfac)Cu(TMVS) compound, by strengthened binding capability using a methoxy ligand. The (hfac)Cu(VTMOS) compound is also known as a compound of profitable competitive power with cheap price and stability because the compound can also keep process repeatability in applying to the manufacturing process of a semiconductor device. The (hfac)Cu(VTMOS) compound, however, is not yet commercialized because MOCVD process technology to use a (hfac)Cu(VTMOS) precursor in the existing LDS is not established yet.
Accordingly, the present invention is directed to provide a method of forming a copper wiring in a semiconductor device to produce a thin copper film of superior film quality because not only can the method realize repeatability of the copper deposition process without new LDS development, but can induce perfect surface absorption reaction in copper deposition, by establishing the MOCVD process technology using a (hfac)Cu(VTMOS) compound as a copper precursor after setting optimum deposition process conditions of a copper deposition equipment.
To achieve these and other advantages and in accordance with the purpose of the present invention, the method of forming a copper wiring in a semiconductor device of the present invention is characterized by comprising: a step of providing a copper deposition equipment to consist of a reaction chamber and a liquid delivery system; a step of loading a wafer on the reaction chamber; a step of evaporating a (hfac)Cu(VTMOS) precursor in the liquid delivery system; a step of flowing the evaporated (hfac)Cu(VTMOS) precursor into the reaction chamber; and a step of depositing copper on the wafer by the method of MOCVD.
The liquid delivery system is one of a direct liquid injection, a control evaporation mixer, a system to have a vaporizer of orifice type and a system to have a vaporizer of spray type.
Process condition, when the liquid delivery system is a direct liquid injection, is: to set a temperature of a vaporizer in the direct liquid injection to 70xc2x0 C. through 120xc2x0 C.; to control a temperature of carrier gas flowing into the vaporizer within 70xc2x0 C. through 140xc2x0 C.; and to keep a temperature of the gas lines and a source line from the vaporizer to the reaction chamber the same with a temperature of the vaporizer.
Process condition, when said liquid delivery system is a control evaporation mixer, is: to keep a temperature of the control valve of the vaporizer in the control evaporation mixer at a room temperature; to set a temperature of the heat exchanger in the vaporizer to 50xc2x0 C. through 120xc2x0 C.; to control a temperature of carrier gas flowing into the control valve within 20xc2x0 C. through 140xc2x0 C.; and to keep a temperature of the gas lines and a source line from the vaporizer to the reaction chamber the same with or 5xc2x0 C. through 20xc2x0 C. higher than a temperature of the heat exchanger.
Process condition, when the liquid delivery system is a system to have a vaporizer of orifice type or a system with a vaporizer of spray type, is: to set a temperature of the vaporizer to 70xc2x0 C. through 120xc2x0 C.; to control a temperature of carrier gas flowing into the vaporizer within 70xc2x0 C. through 140xc2x0 C.; and to keep a temperature of the gas line and a source line from the vaporizer to the reaction chamber the same with a temperature of the vaporizer.
Carrier gas may be one of helium (He), hydrogen (H2) and argon (Ar) at least, and flow of the gas is within 100 sccm through 700 sccm.
A wafer is made by forming an inter-layer insulation film on a semiconductor substrate on which many elements are formed for forming a semiconductor device, performing cleaning after forming contact holes and trenches on the inter-layer insulation film, and forming a diffusion barrier on the surface of the inter-layer insulation film to include the contact holes and trenches.
An inter-layer insulation film is formed, using an insulation film of a low dielectric constant, contact holes and trenches are made by dual damascene type plasma is used when the lower layer is metal such as tungsten (W) or aluminum (Al), or reactive cleaning when it is copper (Cu). A diffusion barrier is formed by one of ionized PVD TiN, CVD TiN, MOCVD TiN, ionized PVD Ta, ionized PVD TaN, CVD Ta, CVD TaN, and CVD WN at least.
Inside temperature of the reaction chamber and a temperature of the shower head of the reaction chamber is within 70xc2x0 C. through 120xc2x0 C., and a temperature of the susceptor plate of the reaction chamber is within 150xc2x0 C. through 280xc2x0 C.
Inside pressure of the reaction chamber is within 0.5 torr through 5 torr, and the interval between the showerhead of the reaction chamber and the susceptor plate of said reaction chamber is within 20 mm through 50 mm.
Flow rate of the (hfac)Cu(VTMOS) precursor is 0.1 sccm through 2.0 sccm, and the (hfac)Cu(VTMOS) precursor may be added at least one of VTMOS of 1% through 30%, Hfac of 0.1% through 10% and Hhfacxc2xdH2O of 0.1% through 10% as an additive.
Additional features and advantages of the invention will be set forth in the description which follows and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.